高强钢框架-屈曲约束支撑体系抗震性能研究

针对高强钢结构在抗震设计中存在的结构延性差、刚度小的问题,提出了高强钢框架-屈曲约束支撑结构。为研究此类结构的抗震性能,对2个足尺单榀单跨单层试件进行了拟静力加载试验,观测了结构在水平往复荷载下变形特征与破坏模式,分析了结构及构件滞回曲线特征,探讨了试件强度退化、刚度退化、塑性变形、耗能能力以及钢框架和屈曲约束支撑的承载力分配和耗能分配。结果表明:高强钢框架-屈曲约束支撑结构滞回性能稳定,塑性变形及耗能能力强,最大水平层间位移角达3%,最大等效阻尼比达30.4%～36.3%。试件破坏模式为整体延性破坏,最终失效模式为柱底翼缘严重局部屈曲以及柱底焊缝撕裂。水平荷载由钢框架与屈曲约束支撑共同承担。当水平位移角在1.5%以内时,塑性变形集中于屈曲约束支撑,钢框架塑性变形仅占总变形的3%～5%,塑性损伤较小,可通过性能化设计方法将结构的塑性变形限制与屈曲约束支撑,可实现震后快速修复。当层间位移角在1.5%以内时,屈曲约束支撑耗能占结构总耗能的95%以上。采用ANSYS软件建立了相应的有限元模型,有限元分析结果与试验结果吻合较好,验证了有限元模型的有效性。

Seismic behavior of high strength steel frame-buckling restrained brace system

Here,aiming at problems of poor ductility and low stiffness of high-strength steel structures in seismic design,a high-strength steel frame-buckling restrained brace structure was proposed.In order to study its seismic behavior,quasi-static loading tests were conducted for two full-scale single-span single-layer specimens,their deformation characteristics and failure modes under horizontal repeated load were observed.Their hysteretic curve characteristics and those of their members were analyzed,their strength degradation,stiffness degradation,plastic deformation and energy dissipation capacity as well as load-bearing capacity distribution and energy dissipation distribution of steel frames and buckling restrained braces were explored.The results showed that high-strength steel frame-buckling restrained brace structure has stable hysteretic performance,strong plastic deformation and energy dissipation capacity,the maximum horizontal interlayer displacement angle is 3%,and the maximum equivalent damping ratio is 30.4%-36.3%;the failure mode of specimens is global ductile failure,and the final failure mode is severe local buckling at column bottom and flange as well as tearing of column bottom weld-line;horizontal load is exerted on steel frame and buckling restrained brace;when horizontal displacement angle is within 1.5%,plastic deformation is concentrated on buckling restrained braces,and plastic deformation of steel frames accounts for only 3%-5%of total deformation,so plastic damage is smaller;the plastic deformation of the structure can be limited to buckling restrained braces using the performance-based design method to realize the rapid post-earthquake repair;when the interlayer displacement angle is within 1.5%,the energy dissipation of buckling restrained braces accounts for more than 95%of the structure total energy dissipation;the corresponding finite element model is established using the software ANSYS,the finite element analysis results agree better with test ones to verify the effectiveness of the finite element model.